Itouch 3G is eating battery fast

It seems like there must be something running while it's in my pocket... I surfed the net for 20 minutes yesterday and at the end of the day I was down to 50% battery... Is there a way to tell what's running, or ??? I'm puzzled.

Okay new issue now, the old one seems to have resolved itself by the way...

Now for the new issue. Last night I turned on my itouch and i imediatly got the 20% battery life warning. Decided to surf the net for a bit anyway, and the battery life climbed back up to ~50% roughly. This morning I put it on the charger, got the notification chime and the lightning bolt charge indicator, but the battery level doesn't rise, it stays red... Please help.